Re: [HACKERS] Safe/Fast I/O ...

On Sun, 12 Apr 1998, Bruce Momjian wrote:

> > As David Gould mentioned, we need to do pre-fetching of data pages
> > somehow.
> > 
> > When doing a sequential scan on a table, the OS is doing a one-page
> > prefetch, which is probably enough.  The problem is index scans of the
> > table.  Those are not sequential in the main heap table (unless it is
> > clustered on the index), so a prefetch would help here a lot.
> > 
> > That is where we need async i/o.  I am looking in BSDI, and I don't see
> > any way to do async i/o.  The only way I can think of doing it is via
> > threads.
> 
> I found it.  It is an fcntl option.  From man fcntl:
> 
>      O_ASYNC      Enable the SIGIO signal to be sent to the process group when
>                   I/O is possible, e.g., upon availability of data to be read.
> 
> Who else supports this?

	FreeBSD...


Marc G. Fournier                                
Systems Administrator @ hub.org 
primary: scrappy@hub.org           secondary: scrappy@{freebsd|postgresql}.org